<template>
    <div class="type-nav">
            <div class="container"  @mouseleave="leaveIndex" @mouseenter="enterShow">
                <h2 class="all">全部商品分类</h2>
                <nav class="nav">
                    <a href="###">服装城</a>
                    <a href="###">美妆馆</a>
                    <a href="###">尚品汇超市</a>
                    <a href="###">全球购</a>
                    <a href="###">闪购</a>
                    <a href="###">团购</a>
                    <a href="###">有趣</a>
                    <a href="###">秒杀</a>
                </nav>
                <!-- 过度动画 -->
                <transition name="sort">
                    <div class="sort" v-show="show">
                        <div class="all-sort-list2" @click="goSearch">
                            <div class="item" v-for="(c1,index) in categoryList" :key="c1.categoryId" :class="{cur:currentIndex==index}">
                                <h3 @mouseenter="changeIndex(index)">
                                    <a :data-categoryName="c1.categoryName" :data-category1Id="c1.categoryId">{{c1.categoryName}}</a>
                                </h3>
                                <!-- js动态控制二三级联动显示与隐藏 -->
                                <div class="item-list clearfix" :style="{display:currentIndex==index ?'block' : 'none'}">
                                    <div class="subitem" v-for="(c2,index) in c1.categoryChild" :key="c2.categoryId">
                                        <dl class="fore">
                                            <dt>
                                                <a :data-categoryName="c2.categoryName" :data-category2Id="c2.categoryId">{{c2.categoryName}}</a>
                                            </dt>
                                            <dd>
                                                <em v-for="(c3,index) in c2.categoryChild" :key="c3.categoryId">
                                                    <a :data-categoryName="c3.categoryName" :data-category3Id="c3.categoryId">{{c3.categoryName}}</a>
                                                </em>
                                            </dd>
                                        </dl>
                                    </div>
                                </div>
                            </div>
                        </div>
                    </div>
                </transition>
            </div>
        </div>
</template>

<script>
import{mapState} from 'vuex';
//下面的引入方式是把lodash全部功能函数引入,最好按需导入
import _ from 'lodash';
//按需导入lodash
// import throttle from 'lodash/throttle';
export default {
  name: 'TypeNav',

  data() {
      return {
          //存储鼠标移动时，一级分类对应的index
          currentIndex:-1,
          show:true
      };
  },

  computed: {
      ...mapState({
          categoryList:(state)=>{
              return state.home.categoryList;
          }
      })
  },

  //组件挂载完毕，向服务器发送请求
  mounted() {
    // this.$store.dispatch('categoryList');
    //判断当前路由是否是search
    if(this.$route.path=='/search'){
        this.show=false;
    }
  },

  methods: {
      //鼠标移入时，列表展示
    enterShow(){
        this.show=true;
    },
      //鼠标滑过事件,鼠标进入获取一级分类的index
    //   changeIndex(index){
    //       this.currentIndex=index;
    //   },
       //解决卡顿现象，用户操作过快
        //防抖和节流，需要有闭包和延迟器的知识，lodash是防抖的封装
        //上面的按需导入使用下面的方法，如果是全局导入，throttle需要变成_.throttle
      changeIndex:_.throttle(function(index) {
          this.currentIndex=index;
      },60),
      //鼠标移除事件，把子元素事件委派给父级
      leaveIndex(){
        //   方法，有缺陷，放到商品分类时，也移除了
        this.currentIndex=-1;
        if(this.$route.path =='/search'){
            this.show=false;
        }
      },
      goSearch(event){
          //子节点的事件委派给了父节点,如何确定点击的是a标签，如何传参和获取参数
          //如一二三级的id和名字
          //把子节点中a标签加上自定义属性:data-categoryName="c1.categoryName"，其余的不加
          //拿到子节点自定义属性,dataset属性
          let element=event.target; //获取当前触发节点，如h3,a,dt,dl
        //   console.log(element.dataset);

          let{categoryname,category1id,category2id,category3id}=element.dataset;//如果categoryname存在一定是a标签
          if(categoryname){
              //怎么确定是一二三级分类
              //整理路由跳转的参数
              let location={name:'search'};
              let query={categoryName:categoryname}
              if(category1id){
                  query.category1Id=category1id;
              }else if(category2id){
                  query.category2Id=category12d;
              }else{
                  query.category3Id=category3id;
              }
              //如果路由跳转时有params参数，也要传递
              if(this.$route.params){
                  let location={name:'search'};
                  location.params=this.$route.params;
                  location.query=query;
                  this.$router.push(location)
              }

          }

      }
  }
};
</script>

<style lang="less" scoped>
.type-nav {
        border-bottom: 2px solid #e1251b;

        .container {
            width: 1200px;
            margin: 0 auto;
            display: flex;
            position: relative;

            .all {
                width: 210px;
                height: 45px;
                background-color: #e1251b;
                line-height: 45px;
                text-align: center;
                color: #fff;
                font-size: 14px;
                font-weight: bold;
            }

            .nav {
                a {
                    height: 45px;
                    margin: 0 22px;
                    line-height: 45px;
                    font-size: 16px;
                    color: #333;
                }
            }

            .sort {
                position: absolute;
                left: 0;
                top: 45px;
                width: 210px;
                height: 461px;
                position: absolute;
                background: #fafafa;
                z-index: 999;

                .all-sort-list2 {
                    .item {
                        h3 {
                            line-height: 30px;
                            font-size: 14px;
                            font-weight: 400;
                            overflow: hidden;
                            padding: 0 20px;
                            margin: 0;

                            a {
                                color: #333;
                            }
                        }

                        .item-list {
                            display: none;
                            position: absolute;
                            width: 734px;
                            min-height: 460px;
                            background: #f7f7f7;
                            left: 210px;
                            border: 1px solid #ddd;
                            top: 0;
                            z-index: 9999 !important;

                            .subitem {
                                float: left;
                                width: 650px;
                                padding: 0 4px 0 8px;

                                dl {
                                    border-top: 1px solid #eee;
                                    padding: 6px 0;
                                    overflow: hidden;
                                    zoom: 1;

                                    &.fore {
                                        border-top: 0;
                                    }

                                    dt {
                                        float: left;
                                        width: 54px;
                                        line-height: 22px;
                                        text-align: right;
                                        padding: 3px 6px 0 0;
                                        font-weight: 700;
                                    }

                                    dd {
                                        float: left;
                                        width: 415px;
                                        padding: 3px 0 0;
                                        overflow: hidden;

                                        em {
                                            float: left;
                                            height: 14px;
                                            line-height: 14px;
                                            padding: 0 8px;
                                            margin-top: 5px;
                                            border-left: 1px solid #ccc;
                                        }
                                    }
                                }
                            }
                        }
                        //暂时注释掉，让js来操控二三级分类的展示
                        // &:hover {
                        //     .item-list {
                        //         display: block;
                        //     }
                        // }
                    }
                    .cur{
                        background-color:skyblue;
                    }
                }
            }
            // 过度动画样式,进入开始状态
            .sort-enter{
                height:0rem;
            }
            .sort-enter-to{
                height:461px;
                // transform:rotate(360deg);//进入时360度旋转
            }
            .sort-enter-active{
                transition: all .5s linear;
            }
        }
    }
</style>